1. Field of the Invention
The invention relates to an actuating system including a base, a movable part which is rotationally movable with respect to the base, and a driving device which is operatively connected to the movable part for rotationally moving it with respect to the base. A control system monitors the movement of the part and ascertains the presence of an obstacle if a parameter representing the movement differs from a stored parameter by more than a threshold limit.
2. Description of the Related Art
U.S. Pat. No. 5,982,126 discloses a control arrangement for a driven locking means, the control arrangement being provided for flaps or doors in a motor vehicle. The control arrangement includes, among other things, a piston-cylinder assembly which exerts an opening force on a rear flap or a vehicle door. Furthermore, a driving unit in the form of an electric motor provides, in conjunction with a cable device, a closing movement of the rear flap or the vehicle door.
The control arrangement includes obstacle recognition providing protection against jamming. For this, the power or the current of the electric motor is sensed and compared with data records which represent the movement of the vehicle door or of the rear flap. The movement is stored in accordance with parameters of the absolute closing force and, among other things, also in accordance with the dissipation of the closing force with regard to the time.
DE 40 36 900 A1 describes a driveable pivoting hinge for flaps or motor-vehicle doors. The pivoting hinge has an electric motor which acts directly on it or on a pivoting lever and brings about an opening and closing movement of the flap. An intermediate mechanism and an overload coupling may be used, if appropriate, for example in order to adapt a standard motor to the fitting situation.
The object of the present invention is to realize a piston-cylinder assembly in conjunction with a driving device having a simple operation and a low outlay on installation.
According to the invention, a sensor detects the rotational speed of a movable part at a reference measuring location, the control system forming a differential of the rotational speed with respect to time. The differential is compared in a comparison unit with a stored differential value which corresponds to a measuring point on a route of movement of the movable part. An obstacle is recognized when there is a difference above a threshold value between the formed differential and the associated stored value.
The advantage of measuring the rotational speed is that an obstacle is immediately detected at the movable part and not, as in the case of measuring the force at the driving unit, as an after effect.
In a further advantageous refinement, the sensor is designed as a rotary potentiometer. The part to be movedxe2x80x94the flap or door in a motor vehicle, executes a rotational movement which can be sensed with sufficient accuracy even by a relatively simple rotary potentiometer.
Each door or flap is subject, within limits, to individual influences which determine the speed of movement of the door or flap. For example, the friction of the hinges may differ. Also, springs which move a rear flap in the opening direction are subject to force tolerances. The ambient temperature can be regarded as a further important parameter in the use of a gas-filled spring device. In order to eliminate all these influences, the stored values which describe an obstacle-free movement of the part to be moved are established by a learning mode.
According to an advantageous embodiment, the movable part enters into operative connection with a lock and the obstacle recognition is limited to a region of movement lying outside a lock movement. The flap lock moves discontinuously and this can only be overcome using excessive effort. The probability of an obstacle being encountered in this short region of movement is negligible.
In one embodiment, a cable device is fastened to the part to be moved, the cable device being guided from a winding device via a deflecting pulley on a piston-cylinder assembly to a fastening point, and so the cable device forms a block and tackle system. A driving device can be used which only has to apply a small driving power.
In a further refinement, a cable of the cable device has a cable guide from the winding device to the deflecting pulley and a fastening point of the cable is arranged on the cable guide. The cable device can therefore be arranged directly on the piston-cylinder assembly without fastening means on the vehicle being necessary. The outlay on installation on the vehicle is at a similarly low level as in the case of a conventional piston-cylinder assembly.
So that the part to be moved is not blocked in the event of a power failure, the driving device has an electromagnetically connected coupling which is opened if the power fails.
For this purpose, a spring-type actuator is connected parallel with the driving device and drives the winding device if the driving device fails. This prevents, for example if the power fails during a closing movement of a flap, the cable of the cable device from lying in an uncontrolled manner in the vehicle and from possibly becoming entangled with the baggage in the trunk.
Furthermore, the cable of the cable device is guided to the piston-cylinder assembly within a sheath, the sheath enclosing the piston-cylinder assembly at least over the cable length which is on the piston-cylinder assembly. The intention is first to protect the cable device and secondly to protect people in the vicinity of the cable device when it is in operation.
For this purpose, the sheath comprises at least one telescopic protective tube.
In order to realize a protective tube having a small diameter and cable guidance which is as parallel as possible to the piston-cylinder assembly, the cable device comprises a first cable-guiding element on a connecting member of the piston rod and a second cable-guiding element on the cylinder of the piston-cylinder assembly.
In a further refinement, the cable-guiding element is designed as an annular bearing which is held by the connecting member. The annular bearings enable the cable-fastening point to move in the circumferential direction, so that no additional distortions or changes in length occur during the operating movement of the piston-cylinder assembly.
The driving unit preferably has a cable-tension sensing device whose signal is passed on to the coupling. During normal operation the cable tension must always lie within a certain operating range. If this operating range is departed from, further measures may be provided so as to enable the cable device to be operated in a manner approximating normal operation.
In order to keep the outlay on sensing as low as possible, the signal of the cable-tension sensing device is in the form of a 0-1 signal.
At a 0 signal from the cable-tension sensing device the coupling is opened. Suppose that an opened rear flap is to be closed. In addition to the driving device which closes the flap, the user presses on it. In the process, the cable tension falls away and the cable could again lie in an uncontrolled manner in the trunk. With the coupling opened, the spring-type actuator provides a driving force for the winding device thereby safeguarding the winding-up process.
In order to keep the structural outlay for the cable-tension sensing device low, the cable-tension sensing device comprises a switch which is actuated by the movement of the cable relative to a cable sheath.
Provision is furthermore made for the actuating system to have an elastic movement buffer which enables a phase displacement of the driving movement of the driving device to the actual movement of the movable part. The intention is to avoid the movable part striking hard against an obstacle. In addition, the driving device is subjected to less stress when an obstacle is encountered.
The sensor used to detect the movement of the part is arranged between the elastic movement buffer and the movable part. This enables the driving unit to operate without delay by means of the buffer.
In a first design variant, the elastic movement buffer is part of the piston-cylinder assembly and when there is a movement of a connecting-member part of the piston-cylinder assembly relative to a reference location of the piston-cylinder assembly the sensor generates a signal indicating an obstacle.
For this purpose, the movement buffer comprises a measuring body in conjunction with a measuring-reference device, the measuring body executing a movement relative to the measuring-reference device when the movable part strikes against an obstacle.
The measuring body and the measuring-reference device are designed as limit switches.
In an alternative embodiment of the actuating system having a base part and a part to be moved, the base part having a driving device which is operatively connected to the part to be moved, the driving device acts directly on a mechanism on the flap. The driving device acts, in one working direction, counter to the force of a piston-cylinder assembly and, in an opposite working direction, operating to maximum effect on a certain region of movement of the part to be moved.
Actuating systems which act directly on a flap or a door and in which the insertion of a cable device can be omitted have the advantage that the opening and the closing movement can be controlled by the driving device. For the driving device, however, the opening movement is associated with a considerably greater power output which would make the driving device more expensive and would enlarge it with regard to the structural space which is required. With the combination of a directly acting actuating system in conjunction with a piston-cylinder assembly the advantages of the drives of the driving device and of the piston-cylinder assembly can be used, in particular since the piston-cylinder assembly often only allows a slow flap movement due to unfavorable coupling points between the base part and the flap. If the driving device engages in an assisting manner in this opening angle region, then the piston-cylinder assembly can be of smaller dimensions with regard to the supporting force.
As a further measure for simplifying the actuating system the driving device and the control system are arranged in a common housing.
Particularly for the version having the directly connected driving unit, the latter has a mechanism, with an elastic transmitting element being arranged in the flow of force coming from the mechanism.
With regard to convenience a lock for the component to be moved can be operated via a remote control, the driving unit being activated by the same triggering signal.
In this case, a permanent signal is connected to touch-control triggering on the remote control for the driving device at the most until an end position of the part to be moved is reached, or an obstacle is encountered or another touch-control triggering takes place. A simple one-button remote control is sufficient.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.